Landsat Missions

Landsat 7

Landsat 7 was launched from Vandenberg Air Force Base in California on April 15, 1999 on a Delta II rocket. The satellite carries the Enhanced Thematic Mapper (ETM+) sensor.

Since June 2003, the sensor has acquired and delivered data with data gaps caused by the Scan Line Corrector (SLC) failure. 

In late 2020, the Landsat 9 satellite will replace the Landsat 7 in orbit. 

Landsat 7 Launch

Landsat 7 Launch

View Launch

Landsat 7 End of Life Plans

Landsat 7 End of Life Plans

News Release

Explorer More Landsat 7

Explorer More Landsat 7

Explorer USGS

 

Illustration of Landsat 7 in orbit

A Rendering of the Landsat 7 Satellite. 

The Landsat 7 satellite orbits the the Earth in a sun-synchronous, near-polar orbit, at an altitude of 705 km (438 mi), inclined at 98.2 degrees, and circles the Earth every 99 minutes.  The satellite has a 16-day repeat cycle with an equatorial crossing time: 10:00 a.m. +/- 15 minutes.  

Landsat 7 data are acquired on the Worldwide Reference System-2 (WRS-2) path/row system, with swath overlap (or sidelap) varying from 7 percent at the Equator to a maximum of approximately 85 percent at extreme latitudes.  

Data products created from over 2.5 million Landsat 7 Enhanced Thematic Mapper Plus (ETM+) scenes are available to download from EarthExplorerGloVis, and the LandsatLook Viewer

Read below for details about Landsat 7 data products.

 

 

 

 

Landsat 7 Spacecraft Facts

  • Power provided by a single Sun-tracking solar array and two 50 Ampere-Hour (AHr), Nickel Cadmium (NiCd) batteries
  • Attitude control provided through four reaction wheels (pitch, yaw, roll, and skew); three 2-channel gyros with celestial drift updating; a static Earth sensor; a 1750 processor; and torque rods and magnetometers for momentum uploading
  • Orbit control and backup momentum unloading provided through a blow-down monopropellant hydrazine system with a single tank containing 270 pounds of hydrazine, associated plumbing, and twelve 1-pound-thrust jets
  • Weight: approx. 4,800 lbs (2,200 kg)
  • Length: 4.3 m (14 ft)
  • Diameter: 2.8 m (9 ft)
  • Direct Downlink with Solid State Recorders (SSR)
  • Data rate: 150 Mbps

Landsat 7 Instrument

Landsat 7 carries the Enhanced Thematic Mapper Plus (ETM+) sensor, an improved version of the Thematic Mapper instruments that were onboard Landsat 4 and Landsat 5. Landsat 7 products are delivered as 8-bit images with 256 grey levels. Descriptions of Landsat 7 band designations and comparisons of all Landsat sensors are available.

Enhanced Thematic Mapper Plus (ETM+)

  • Eight spectral bands, including a pan and thermal band:
    • Band 1 Visible (0.45 - 0.52 µm) 30 m
    • Band 2 Visible (0.52 - 0.60 µm) 30 m
    • Band 3 Visible (0.63 - 0.69 µm) 30 m
    • Band 4 Near-Infrared (0.77 - 0.90 µm) 30 m
    • Band 5 Near-Infrared (1.55 - 1.75 µm) 30 m
    • Band 6 Thermal (10.40 - 12.50 µm) 60 m Low Gain / High Gain
    • Band 7 Mid-Infrared (2.08 - 2.35 µm) 30 m
    • Band 8 Panchromatic (PAN) (0.52 - 0.90 µm) 15 m
  • Ground Sampling Interval (pixel size): 30 m reflective, 60 m thermal
  • Added the Band 6 Low and High gain 60 m thermal bands
  • On-board calibration was added to Landsat 7: a Full Aperture Solar Calibrator (FASC) and a Partial Aperture Solar Calibrator (PASC), in addition to the 2 calibration lamps

Landsat 7 Data Products

Landsat 7 data products are consistent with all Landsat standard Level-1 data products, using the specifications described on the Landsat Processing Details page.

Landsat 7 Scan Line Corrector (SLC) Failure

Illustration of the Landsat 7 Scan Line Corrector (SLC) Failure

Above: Illustration of the Landsat 7 Scan Line Corrector (SLC) Failure Below: Example of SLC-off scene. 

On May 31, 2003, the Scan Line Corrector (SLC), which compensates for the forward motion of the satellite, failed. Subsequent efforts to recover the SLC were not successful, and the failure is permanent. Without an operating SLC, the sensor’s line of sight traces a zig-zag pattern along the satellite ground track.

As a result, the imaged area is duplicated, with a width that increases toward the edge of the scene.  When the Level-1 data are processed, the duplicated areas are removed, leaving data gaps. Although these scenes only have 78 percent of their pixels remaining after the duplicated areas are removed, these data are still some of the most geometrically and radiometrically accurate of all civilian satellite data in the world.

A Landsat 7 SLC-off Scene Example

A number of papers were written about the Landsat 7 Scan Line Corrector: 

Landsat 7 End of Life Plans (View this USGS News Release)

On February 7, 2017, the twentieth and final Delta-I (inclination) maneuver took place. Delta-I maneuvers keep the spacecraft in the correct orbit to ensure the satellite maintains its 10:00 am local mean time (LMT) acquisitions.  The satellite reached its peak outermost boundary of 10:14:58 Mean Local Time (MLT) on August 11, 2017. The satellite will now drift in its inclination over the next four years, falling back to 9:15 by early 2020.

By the time the Landsat 9 satellite launches in late 2020, Landsat 7 will be at a lower orbit, allowing Landsat 9 to move into the 705-kilometer standard orbit altitude after launch.  Once Landsat 7 reaches a 9:15 am (LMT) acquisition time, it will no longer be providing valid science data and the satellite will be decommissioned.  Landsat 9 will allow the continuance of an 8-day offset for acquisitions with Landsat 8.

NASA Restore_L Mission

Landsat 7 is a candidate for the NASA Restore_L Robotic Servicing Mission. The mission - the first of its kind in low-Earth orbit - will provide Landsat 7 with the needed fuel for a successful decommissioning. This added fuel could also provide other possibilities: Landsat 7 could be turned into a transfer radiometer; it could fly below Landsat 8 and Landsat 9, as well as the European Space Agency’s Sentinel-2A and 2B satellites; or it could serve as a calibration instrument. The additional fuel could also potentially extend its science mission.

 

Landsat 7 Data User's Handbook 

Landsat 7 Information (NASA Landsat Science)

Landsat 8/LDCM’s Underfly with Landsat 7: In March 2013, the Landsat 8 satellite (then known as LDCM) was in position under Landsat 7 to collect near-coincident data for calibration activities.